1. Field of the Invention
The invention relates to a chain store and a process for controlling the chain store.
The chain store and the process can be used for the temporary storage of articles or products of the same type.
The articles or products may be, for example, chocolate bars which are transported from a production apparatus to at least one packaging apparatus. However, the product may consist not of chocolate bars but of other sweet or nonsweet foods in the form of pieces, for example bakery articles, or of cans or other containers having any filling or of components for mechanical engineering, for example ball bearings, which are transported to a packaging apparatus or other processing apparatus.
2. Description of the Prior Art
In the case of known means for the production and packing of chocolate bars, the bars produced by a production apparatus are transported via a feed belt to a chain store and then through this to, packaging apparatuses. The chain store serves in this case as a compensating apparatus for compensating variations in the feed rate of bars or the packing rate of the packing apparatus and complete stoppages of operation of the production apparatus or of the packing apparatus, for example lasting for 5 min to 45 min. A chain store of this type typically has 150 to about 1200 gondolas attached to two continuous chains and having a plurality of shelves for holding one row of bars each. Each chain is deflected by a plurality of chain wheels mounted in a frame and by a plurality of chain wheels mounted on vertically displaceable carriages and forms a number of loops.
In the case of known chain stores, those chains of the loading and unloading side which are each driven by a drive motor are intermittently moved, i.e. they are stationary while products are being loaded onto the shelves at the loading station and are being unloaded again from the shelves at the unloading station. The store operates according to the xe2x80x9cfirst-inxe2x80x9d/xe2x80x9cfirst-outxe2x80x9d principle and makes it possible in particular to operate infeed and outflow at different speeds.
Thus, one storage level after the other is loaded for filling the chain store, for which purpose a loading motor controlled by a control mechanism moves the loading side stepwise past the loading station, while the unloading side controllable by an unloading motor is blocked. For removal of articles from the store, the unloading side is moved stepwise past the unloading station so that the storage levels can likewise be unloaded stepwise.
Because of the requirement for realizing constantly higher capacities and for increasing the loading and unloading frequency of the store, the gondolas rock to an increasing extent at the deflection wheels. This can lead to rocking of the gondolas over the total length of the chain at a sufficiently high cycle frequency or transport velocity, which in the extreme case results in the goods being thrown out of the gondolas.
This disadvantage has long been known to a person skilled in the art. Thus, for example, U.S. Pat. No. 4,813,752 discloses an antioscillation system which, by rolling of gear wheels in the manner of a planetary gear, ensures that the gondolas are guided perpendicularly and rigidly in the region of the deflection pulleys, in order thus to avoid disadvantageous rocking movements. Said system comprises gear wheels which are arranged on the deflection pulleys and the gondolas and engage one another with their teeth during the deflection.
This antioscillation system has the disadvantage that the gondolas are guided at the deflection pulleys so rigidly that the goods present on the storage levels may be thrown off owing to the centrifugal force acting only on them in this casexe2x80x94and no longer on the gondolasxe2x80x94and produced by the deflection, if the velocity at which the gondolas are guided around the deflection pulleys exceeds a limit dependent on the mass of the goods.
It is the object of the invention to propose a chain store by means of which the abovementioned disadvantage can be at least partly avoided, so that in particular the loading frequency can be increased compared with the conventional chain stores.
This object is achieved, according to the invention, by a chain store comprising two continuous chains which together carry gondolas serving for holding goods and are driven together by gear wheels or chain wheels rigidly connected to one another, each chain being guided by means of at least three upper and three lower stationary deflection pulleys and by means of deflection pulleys, two each of which are freely rotatably mounted one on top of the other in a vertically displaceable carriage, in such a way
that the chain in each case passes from an upper stationary deflection pulley perpendicularly downwards to an upper deflection pulley of a carriage and from there perpendicularly upwards to the next stationary upper deflection pulley
that it in each case passes from a lower stationary deflection pulley perpendicularly upwards to the lower deflection pulley of a carriage and from there perpendicularly downwards to the next stationary lower deflection pulley,
that it passes from the last upper stationary deflection pulley to the last lower stationary deflection pulley and from the first lower stationary deflection pulley to the first upper stationary deflection pulley,
on the one hand a loading station and on the other hand an unloading station being provided on the two outer sides of the chain, and one drive apparatus each being coordinated with the loading side and unloading side and each driving the upper or lower stationary outermost deflection pulley coordinated with the loading side or unloading side, wherein additional drive means are present for optionally moving the carriages vertically, independently of the driving of the loading and unloading side.
A further object of the invention is a process for controlling a chain store as mentioned above, the drive motor drives the chain so that, whenever possible, the carriages are present in the upper half of the rails guiding them, preferably assume the highest possible vertical position, so that disadvantageous rocking of the gondolas is avoided thereby.